This invention relates generally to the testing of kinescopes during production and particularly to an apparatus for testing for electrical breakdown of the frit seal of such tubes.
Kinescopes for television include a funnel, a neck and a faceplate panel. Typically the funnel and neck are integrally fabricated with the neck portion attached to the narrow end of the funnel. The faceplate panel is affixed to the wide end of the funnel by a fritting process which hermetically couples the two elements. The inside of the funnel, and a portion of the neck, are coated with a conductive material which is biased with the high positive voltage during the operation of the tube to accelerate the electron beams toward the faceplate panel. A problem sometimes arises when the frit seal is made electrically conductive by the diffusion of the electrical coating material into the fritting material or by other contaminants or pin holes in the frit seal. Any of these conditions make the tube unacceptable. Every kinescope therefore must be checked for an electrically conductive frit prior to further processing.
The instant invention addresses this problem by the provision of an apparatus for automatically checking kinescopes for electrical breakdown of the frit seal.